Many adults develop the wish to have children. However, it is commonly known that becoming pregnant can be a non-trivial objective. Depending on a variety of factors, it may be hard (or ultimately impossible) to even start the pregnancy. One of those factors is the precise moment of conception. It is only during the most fertile days of the menstrual cycle that the optimal conditions for getting pregnant are satisfied.
The woman's fertility varies throughout her monthly cycle, and actually, conception can only occur shortly (within 12 hours) after the ovulation. The ovum released during ovulation only has a lifetime of up to 48 hours and the sperm survives in the vaginal environment for an average of 60 to 120 hours. During the fertile period, the vaginal environment becomes more welcoming and friendly to sperm. Cervical mucus becomes less acidic and more elastic and the cervix moves from a low, firm, dry and closed position to being soft, high and open. All these changes facilitate the passage of sperm to the uterus and the Fallopian tubes, where fertilization of the released ovum usually occurs.
Because the day of ovulation is important to understanding fertility, many women tend to monitor their bodies for signs of ovulation. However, although many women think they know when they ovulate, it is quite likely that not a lot do actually know. Hence, several tests and tools have been developed and are commercially available to assist in predicting the fertile period.
Basal (or Core) Body Temperature (BBT) Thermometers are used to measure the core body temperature at certain times of the day. When women ovulate, their core temperature rises by half a degree to a full degree because of the extra progesterone in their body. Although the temperature can fluctuate throughout the month, a sustained increase in body temperature is indicative of the ovulation having occurred. With BBT thermometers, the temperature is tracked during the monthly period, typically by a daily oral measurement protocol, and the periodic nature of the woman's cycle can be used to predict the fertile period after a few months of measurements.
A similar approach is applied by Luteinizing Hormone (LH) Testing Kits which measure the LH levels in the woman's urine. Luteinizing hormone LH is produced by gonadotroph cells in the anterior pituitary gland. An acute rise of LH triggers ovulation. LH Testing Kits are available in the form of dipsticks which change color if ovulation will happen within 24 to 48 hours. The fertility tracking using these kits is similar to BBT thermometers and requires a strict protocol since the LH levels have to be measured at the same time every day.
The aforementioned methods are usually combined with electronic monitoring devices which assist a person to follow the protocol. These monitoring devices usually keep track of the measurements and indicate when another measurement is required. Furthermore, by tracking the measurements of several methods and combining these with the periodic nature of the menstrual cycle, the monitoring devices are capable of predicting the fertile periods very precisely.
The monitoring devices assist in following the protocol but will not replace it. Hence, the fairly small but non-negligible burden of explicit protocol remains. Its daily nature, combined with the short fertile time window, means that no days shall be skipped, and in many cases, this protocol has to be sustained for months in a row. Especially, the strict timing of BBT and LH measurements can be hampering in real-life settings, and a deviation may reduce the reliability of the outcome. Furthermore, to be forced to take measurements at a certain time slot can pose privacy issues, as one is not always under control of the social setting at a given moment of the day. Hence, there is a need for an improved device and method.
JP 2006-094969 discloses a method and an apparatus for determining female menstrual cycles by measuring continuously a heart rate of a subject. The menstrual cycle and ovulation dates are estimated by comparing the day average value with the monthly average value of the heart rate.